The present invention relates to laminate structural panels and, more specifically, to light-weight laminates having desirable structural characteristics.
A number of approaches have been taken to provide improved structural characteristics of panels without substantially increasing weight or materials cost. Composites of steel sheets having a solid polymer core have been used in applications where sound deadening and vibration dampers are required. These composites, however, suffer from a number of drawbacks such as low resistance to denting and a lack of desired stiffness in many applications. In U.S. Pat. No. 5,985,457 entitled STRUCTURAL PANEL WITH KRAFT PAPER CORE BETWEEN METAL SKINS, the entire disclosure of which is incorporated herein by reference, structural panels are disclosed which are laminate structures having metals skins separated by and bonded to an intervening layer of paper. The laminates described therein have high specific stiffness and dent resistance.
In co-pending U.S. patent application Ser. No. 09/342,690, filed Jun. 29, 1999, entitled, CARGO VEHICLE WALL, the entire disclosure of which is incorporated by reference, truck trailers having walls formed of laminates of metal skins and paper are described. The truck walls provide good structural characteristics while still minimizing weight and cost.
In U.S. Pat. No. 6,171,705, entitled, IMPROVED STRUCTURAL PANEL AND METHOD OF MANUFACTURE, the entire disclosure of which is incorporated by reference, various improvements to metal/paper/metal laminates are disclosed, including improved methods of manufacture.
Despite the numerous advantages of the aforementioned metal/paper/metal laminates, the present inventor has identified a need in some applications for a reduced-weight version of the inventive panels, particularly where large-area panels are fabricated. The present invention achieves this goal.
In one aspect a structural laminate is provided having first and second skins of sheet metal. A fibrous core layer is provided between the sheet metal skins and is bonded to the skins. A plurality of holes are formed in the fibrous layer, each hole having a an area of from about 0.008 square inch to about 0.2 square inch. In one aspect, the fibrous core layer is impregnated with an adhesive resin. In another aspect layers of adhesive are placed between the core material and the skins. The resulting laminate structure is strong and lightweight.